Sokrates: “I also see, Ion, and I am about to show you what I think this means. For talking well about Homer is not some skill within you—as I was just saying—but it is a divine power that moves you, just as in that stone which Euripides calls a ‘Magnet” but which most people call Herakleian. For this stone not only moves iron rings but it also imbues the rings with the same power so that they can do the same thing as the stone in turn—they move other rings and as a result there is a great chain of iron and rings connected to each other. But the power from that stone runs through them all. In this way, the Muse herself makes people inspired, and a linked chain of inspired people extend from her.
All the good poets of epic utter those beautiful poems not because of skill but because they are inspired and possessed—(...) For a poet is an empty thing—winged, and sacred and not capable of composing before it is inspired and out of mind, when thought is no longer inside. Until one has gained this state, every person is incapable of composing or giving oracles. (...)
-- Ion (533d-534e)